1. Field of the Invention
This invention relates to the field of milking machine systems.
2. Description of Prior Art
The regulation of vacuum in cow milking machine systems is, at present, generally poor. Thus, for example, when air is drawn into the vacuum line through one or more sets of teat cups, the pressure increase (vacuum decrease) in the system may be so great that the teat cups fall from the udders of large numbers of cattle. Conversely, the pressure may at times be so low (vacuum so high) that the teats are injured. There exists a major need for a milking machine system capable of milking large numbers of cows, and wherein the pressure (vacuum) stays substantially constant, at all times, regardless of such factors as the drawing-in of air through the teat cups for one, or a number of, cows.
The vacuum regulators in prior-art milking systems were normally high-inertia devices which sensed the pressure at regions of high air velocity--which velocity created localized pressure changes and thus resulted in errors. Because of the high inertia, changes in line pressure could not be compensated for with sufficient rapidity. Prior-art regulators in milking systems were also characterized by the presence of air valves which were affected by air flow velocity and which could not pass volumes of air adequate to compensate rapidly for sudden changes in line pressure. Such regulators required major axial movement of the air valves, with consequent excessive changes in the forces exerted by the biasing springs. Furthermore, such biasing springs were often undesirably large and heavy. These, and other, factors resulted in the unsatisfactory pressure regulation outlined in the preceding paragraph.
There exist large numbers of vacuum regulators in arts not related to milking machine systems. Such regulators are, insofar as applicant is aware, unsatisfactory in the milking machine art. There are numerous reasons for this, including one or more of the following: (a) Such vacuum regulators are not adapted to handle the high-flow and dynamic conditions present in large milking systems. (b) Such regulators were of the "series" type, which would, if incorporated in a vacuum line to a milking machine, create major problems relative to cleaning of the regulator and relative to danger of damage to the vacuum pump. (c) Such regulators were of complex, and thus expensive, construction.